Discharge apparatus for a silo

Abstract

An apparatus for discharging fine material from a silo with a cylindrical wall 2 and a bottom 3 provided with a central hole 11 and a discharge aperture 4, comprises: a cylindrical skirt 5 suspended from the wall above the bottom and having a crenellated edge formed of projections 6 alternating with spaces 7; a mobile discharge arm 8, having a central connection and two ends trapped in a peripheral zone between the skirt and the periphery of the bottom, for transferring fine material to the discharge aperture; rollers 9, 10 disposed on the ends of the arm for directing the displacement of the arm in cooperation with the skirt; a central revolving shaft 13 passing through the central hole to engage the central connection for rotating the arm; and first and second actuating cylinders 17, 18 acting on the central shaft in substantially perpendicular directions for alternately moving the shaft along the periphery of the central hole such that when a first roller advances on a route outside a projection a corresponding end of the arm advances under the projection, and the second roller is trapped in a space.

We claim: 
     
       1. An apparatus for discharging fine material from a silo having a cylindrical wall (2) and a bottom (3) with a discharge aperture (4), comprising: (a) a discharge arm (8) having two opposed ends, said arm being displaceable over the bottom of the silo, to transfer fine material to a vicinity of said discharge aperture;   (b) means for rotating said discharge arm about a central connection thereof; and   (c) first and second actuating means (17, 18) acting on the central connection in substantially perpendicular directions, for moving said central connection along a generally rectangular trajectory.   
     
     
       2. An apparatus as claimed in claim 1, wherein each of the first and second actuating means comprises a hydraulic cylinder having a body and a piston traveling between two extreme positions, said cylinders operating alternately in such a way that the piston of one cylinder stops at an extreme position while the piston of the other cylinder displaces said central connection. 
     
     
       3. An apparatus as claimed in claim 1, wherein the bottom of said silo has a hole in a central area for defining said rectangular trajectory of the central connection along a periphery of the hole. 
     
     
       4. An apparatus as claimed in claim 1, further comprising guiding means, cooperatively arranged on the arm and on the wall, for directing the trajectory of the arm ends. 
     
     
       5. An apparatus as claimed in claim 1, wherein the means for rotating said discharge arm comprises a driven revolving shaft having one end journalled in the central connection and another, opposite end connected to a support. 
     
     
       6. An apparatus as claimed in claim 5, wherein the bottom of said silo has a hole in a central area, and the actuating means are coupled to said shaft for directing the displacement of the shaft along a periphery of the hole. 
     
     
       7. An apparatus as claimed in claim 4, wherein said guiding means comprises: a skirt suspended along a periphery of said wall and having a crenellated edge formed by projections alternating with spaces; and   first and second rollers individually mounted on opposite ends of the arm with rotational axes thereof perpendicular to the bottom of the silo such that said first roller advances on a route outside the skirt guided by a projection while a corresponding arm end advances under said projection, when said second roller is trapped in a space between two adjacent projections.   
     
     
       8. An apparatus for discharging fine material from a silo having a cylindrical wall and a bottom provided with a central hole and a discharge aperture, comprising: (a) a cylindrical counter surface, suspended from said wall above the bottom;   (b) a mobile discharge arm, having a central connection and two ends trapped in a peripheral zone defined between the counter surface and a periphery of said bottom, for transferring fine material in a vicinity of said discharge aperture;   (c) leading means disposed on said arm ends, for directing the displacement of said arm in cooperation with said counter surface;   (d) a central revolving shaft, passing through said central hole and engaging said central connection, for rotating said arm; and   (e) first and second actuating means acting on the central shaft in substantially perpendicular directions for alternately moving said shaft along a periphery of said central hole.   
     
     
       9. An apparatus as claimed in claim 8, wherein the counter surface comprises a plurality of projections arranged in a circle close to the wall of the silo, forming a like number of spaces between the projections. 
     
     
       10. An apparatus as claimed in claim 9, wherein the projections (6) are located at a lower edge of a skirt connected to the wall of the silo. 
     
     
       11. An apparatus as claimed in claim 9 or 10, wherein the projections are substantially square. 
     
     
       12. An apparatus as claimed in claim 9, wherein said leading means are rollers journalled at the ends of the discharge arm having a diameter smaller than the spaces between the projections. 
     
     
       13. An apparatus as claimed in claim 12, wherein the rollers are arranged to move from one space between the projections to another in the peripheral zone, at an outer side of the projections. 
     
     
       14. An apparatus as claimed in claim 8, wherein each actuating means comprises a hydraulic cylinder having a body and a piston for traveling between two extreme positions, said cylinders operating alternately such that, when one piston stops at an extreme position, the other piston displaces the central connection. 
     
     
       15. An apparatus as claimed in claim 14, wherein the body of each said cylinder is fixed to the bottom of the silo. 
     
     
       16. An apparatus as claimed in claim 15, wherein the piston of each cylinder is connected via a connecting piece to said revolving shaft.